Different expressions were proposed for the computation of dissolved gas levels in the stilling basin and the river. Through high speed jet test and the device designed by authors TDG generation processes was analyzed deeply. It was found shows that the huge energy takes air bubbles into the bottom of the stilling basin during spill release, which makes air solubility increase along the depth of stilling basin,therefore the water in the bottom of the stilling basin can dissolve more gas than surface. Through strong turbulence in stilling basin the water with high concentration TDG mixes with the low concentration water, so dissolved gas in the part of water in stilling basin become supersaturation. It was also found that the velocity of supersaturation TDG increase with the levels of disorder without aerating.
